A comparison of spinergy versus standard steel-spoke wheelchair wheels

OBJECTIVES: To compare the energy efficiency of straight-line wheeling using Spinergy wheels as compared with standard steel-spoke wheels, and to assess the 2 wheels in terms of user comfort and wheeling preference during a wheeling course with multiple turns and surfaces. DESIGN: Nonblinded randomized crossover trial. SETTING: Rehabilitation center. PARTICIPANTS: Twenty persons with paraplegia (neurologic level T6 and below). INTERVENTION: Wheeling a straight line and obstacle course with Spinergy or standard spoke wheelchair wheels. MAIN OUTCOME MEASURES: Velocity and Physiological Cost Index (PCI) while wheeling over ground at a self-selected pace, and the User Preference Questionnaire after wheeling an obstacle course, using Spinergy or standard spoke wheelchair wheels. RESULTS: There was no significant difference in wheeling energy efficiency between the Spinergy and the steel-spoke wheels as measured by PCI ( P =.975). When rated for overall comfort, the Spinergy wheels were preferred over steel-spoke wheels ( P =.002). CONCLUSIONS: Spinergy wheels provided a more comfortable ride, but did not differ from standard steel-spoked wheels in terms of energy efficiency. The increased comfort may have important implications in patient management of pain and spasticity.     

Exploring the ecological validity and variability of a 10-min bout of wheeling

Purpose: To determine the ecological validity of using able-bodied participants to perform a 10-min wheeling trial by (1) evaluating changes in biomechanics over the trial in manual wheelchair users and able-bodied participants naïve to wheeling and (2) describing differences in changes and variability between groups.

Materials and methods: Manual wheelchair users (n?=?7, 2–27?years’ experience) and able-bodied participants (n?=?11) wheeled for 10?min. Kinetic and temporal variables were collected and averaged over each minute, while wheeling strategy (movement pattern) was categorized at minutes 1 and 10.

Results: There was a main effect of time for push angle, and a main effect of group for average push angle, tangential force and total force. Manual wheelchair users used larger push angles and forces compared to able-bodied participants. Surprisingly, intercycle variability did not differ between groups.

Conclusion: Using able-bodied participants to represent manual wheelchair users performing a 10-min wheeling trial is not ecologically valid and caution should be used when interpreting push angle and forces applied to the pushrim. Considering that push angle was the only variable that demonstrated a main effect of time, long durations (e.g., 10?min) of wheeling may be appropriate for use in study designs acknowledging potential changes in wheeling strategy and push angle.

• Implications for Rehabilitation

• Some experienced wheelchair users and non-wheelchair users modify their movement pattern from an arc to a circular pattern within a 10-min wheeling trial.

• There are clear biomechanical differences in push angle and forces applied to the pushrim between wheelchair users with experience and able-bodied non-wheelchair users.

• Able-bodied participants who have no prior manual wheeling experience are no more variable than long-term wheelchair users.

• Variability may play an important role in wheelchair propulsion.

     

User assessment of manual wheelchair ride comfort and ergonomics

OBJECTIVE: To examine wheelchair-user perceived ride comfort during propulsion and to compare the ride comfort of ultralight and lightweight manual wheelchairs. An ultralight wheelchair is defined as having a high degree of adjustability, whereas a lightweight wheelchair has minimal adjustability. DESIGN AND PARTICIPANTS: Repeated measures design of a sample of 30 community-dwelling manual wheelchair users evaluating 7 different manual wheelchairs over an activities of daily living course. SETTING: A rehabilitation engineering center. MAIN OUTCOME MEASURES: Subject ratings of perceived ride comfort and basic ergonomics while propelling over the activities of daily living course. Ratings were recorded for each wheelchair on individual tasks and for the course overall. RESULTS: The Invacare Action XT wheelchair was ranked best for both ride comfort and basic ergonomics. The ride-comfort scores (p < .05) and wheelchair ergonomics ratings (p < .05) for the ultralight wheelchair group were significantly different from those for lightweight wheelchair group. CONCLUSION: There are differences in perceived ride comfort and basic ergonomics between the designs of the wheelchairs (lightweight vs ultralight). Subjects perceived that ultralight wheelchairs were more comfortable and had better basic ergonomics than lightweight wheelchairs.     

The effect of rear wheel camber in manual wheelchair propulsion

Eight nonimpaired subjects participated in a wheelchair exercise test using a motor-driven treadmill in order to study the effect of rear wheel camber on wheelchair ambulation. The test consisted of four runs with rear wheels in 0, 3, 6, and 9 degrees camber at four speed steps of 2, 3, 4, and 5 km/hr. There were no significant effects upon oxygen cost, heart rate, and mechanical efficiency. The kinematic parameters of push time, push angle, and abduction showed differences between 3 and 6 degrees camber. The relationship between the findings, using surface EMG results for six shoulder muscles, is discussed. For one subject, data were extended to study the angular velocities of shoulder and elbow.     

Variable-ratio pushrim-activated power-assist wheelchair eases wheeling over a variety of terrains for elders

OBJECTIVES: To test (1) whether a prototype variable-ratio pushrim-activated power-assist wheelchair would decrease effort and perceived exertion associated with wheeling and (2) whether the prototype would be acceptable to elders. DESIGN: Repeated-measures design. SETTING: Biomechanics laboratory. PARTICIPANTS: Eleven elderly wheelers (mean age +/- standard deviation, 70.7+/-7.8 y). INTERVENTIONS: Wheelers propelled their own wheelchairs and the prototype on a level surface, a carpet, and an incline. MAIN OUTCOME MEASURES: Surface electromyographic activity from upper limb and torso, heart rate, number of pushes, category-ratio scale of perceived exertion, and Consumer Assessment of Power Assist Wheelchairs. RESULTS: Compared with subjects' own manual wheelchairs, the prototype was associated with lower heart rate elevation (P<.0125), lower perceived exertion (P<.0125), and reduced electromyographic activity in 5 of 8 muscles. Of the 11 participants, 10 found the prototype to be "very easy" or "easy" to push on level and inclined surfaces; 9 gave that assessment on carpeted and inclined surfaces. Seven would "definitely" or "probably" trade their manual chairs for the power-assist chair if given the opportunity. Nine thought they would venture to new and different places in a power-assist wheelchair. Time and number of pushes to complete tasks did not differ significantly between chairs. CONCLUSIONS: The prototype reduced the effort associated with wheeling and was an acceptable alternative to manual wheelchairs. Further testing outside the laboratory is warranted.     

Nursing Students' Self-Attributions of Skill, Comfort, and Approach When Imagining Themselves Caring for Persons with Physical Impairments Due to Developmental Disability

Fifty-two nursing students made self-attributions along a series of scales pertaining to skill level, comfort level, and interpersonal approach when imagining themselves providing care to an individual with no apparent physical disability, to a person who requires the use of a power-assisted wheelchair due to developmental disability, and to a person who requires the use of a power-assisted wheelchair and manual communication board. Factor analysis was used to reduce the self-attributional data to two dimensions: one reflecting perceived skill and comfort level, and the other reflecting the assumption of a rational versus intuitive clinical approach. Students attributed lower levels of skill and comfort to themselves, as well as a more intuitive approach, when imagining themselves caring for one who uses a power-assisted wheelchair, and to a greater extent, when imagining themselves caring for one who uses a wheelchair and a communication board, than for one without an apparent disability. Correlations of student age and number of years in nursing practice with self-attributions were investigated.     

Mechanical effects of rear-wheel camber on wheelchairs

Giving the rear wheels of manually propelled wheelchairs negative camber (by angling them such that the bottoms of the wheels are farther apart than the tops) has become increasingly popular, especially among active users. This study's purpose was to evaluate how changing camber affects a wheelchair's mechanics and the extent of these changes. Using a representative wheelchair occupied by an anthropomorphic dummy, we altered the camber from +15 degrees to -15 degrees and measured the effects on nine selected variables. In addition to increasing the wheelchair's track width, negative camber increases the wheelchair's wheelbase and decreases the height of the frame. With negative camber, the center of gravity (CG) of the occupied wheelchair moves backwards. Negative camber causes a backwards tilt of the frame which, in turn, causes toe-out of the rear wheels, a positive caster-inclination angle and an increase in the caster-trail distance. It is apparent that a change in one component of a wheelchair can affect many others, which should be taken into consideration and, where appropriate, compensated for when changing the camber of the wheelchair.     

Improved efficiency with a wheelchair propelled by the legs using voluntary activity or electric stimulation

OBJECTIVE: To determine whether a new leg-propelled wheelchair provides enhanced efficiency and mobility to wheelchair users. DESIGN: Observational; subjects were tested while wheeling with the arms and legs and while walking (where possible) for 4-minute periods in random order with approximately 10-minute rest periods between exercise sets. SETTING: Tests were done on an indoor 200-meter track. PATIENTS: Group 1, 13 controls; group 2, 9 persons with complete spinal cord injury (SCI); group 3, 13 persons with other motor disorders (retaining some voluntary control of the legs). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Physiological Cost Index (PCI), (computed as change in heart rate divided by velocity of movement) and oxygen consumption (VO(2)) RESULTS: Arm wheeling took significantly more effort (mean PCI =.52 beats/m) than walking (.33 beats/m) in control subjects. Leg wheeling was most efficient (.23), requiring less than half the effort of arm wheeling and 30% less effort than walking. For SCI subjects, leg wheeling with functional electric stimulation (FES) required less than half the effort (.18) of arm wheeling (.40). The FES group could not walk. Subjects in group 3 could walk, but with substantial effort (1.81) compared with arm (.76) or leg wheeling (.64). Results for VO(2) were similar. CONCLUSIONS: Better wheelchair efficiency can be obtained for many disabled individuals, by moving the leg muscles voluntarily or with FES.     

Longitudinal assessment of vibrations during manual and power wheelchair driving over select sidewalk surfaces

Wheelchair users rely on their wheelchairs for mobility for extended periods of time every day. According to the International Standards Organization 2631-1 standard on human vibration, individuals in a seated position when exposed to whole-body vibrations (WBV) are at risk of injury. This study evaluated vibration exposure during manual and power wheelchair driving over nine sidewalk surfaces and differences in vibration exposure over 3 years. Ten nondisabled subjects were asked to drive a manual wheelchair at 1 m/s and a power wheelchair at 1 m/s and 2 m/s over nine sidewalk surfaces while WBV were measured at the seat and footrest of the wheelchair. At 1 m/s, significant differences existed between surfaces and years at both the seat and the footrest for the manual and power wheelchair users. At 2 m/s, significant differences existed between surfaces and years at the seat and the footrest for power wheelchair users. Our results show that both manual and power wheelchair users may be at risk for secondary injuries from WBV when traveling over certain surfaces.     

Effect of system tilt and seat-to-backrest angles on load sustained by shoulder during wheelchair propulsion

This study determined the effect of system tilt angle (STA) and seat-to-backrest angle (SBA) changes on the load sustained by the shoulder during manual wheelchair propulsion. Fourteen elderly participants (mean +/- standard deviation age 68.2 +/- 5.2 years) were recruited. Combinations of three STAs (0 degrees , 5 degrees , and 10 degrees ) and three SBAs (95 degrees , 100 degrees , and 105 degrees ) were randomly tested. The initial position of the wheel axle was held constant with respect to the participant's shoulder position in each condition (horizontal: 4 cm forward of shoulder, vertical: 110 degrees to 120 degrees elbow extension). The shoulder load was estimated by the joint moments. The analysis did not reveal any significant differences between shoulder joint moments (average and peak) for the various STA and SBA combinations. Changing the seat angle while keeping the wheel-axle position constant maintained the shoulder load at the same level. Thus, seat angle can be determined with the goals of user comfort and pressure modulation at the seat interface for alleviating pressure ulcers without increasing risk of overuse shoulder injuries.     

Evaluation of manual wheelchairs by individuals with spinal cord injuries

Purpose.?The aim of this study was to investigate how adults with spinal cord injury assess their satisfaction regarding various aspects and use of their manual wheelchair.

Method.?The Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST 2.0) together with seven additional questions was sent to 205 adults with SCI.

Results.?One hundred and twenty-four responses were available. The QUEST 2.0 showed a high level of satisfaction with manual wheelchair properties. However, the respondents were less satisfied with the services offered. Ease of use and comfort were identified as most important. Eighty-nine percent of the respondents rated their level of satisfaction as ‘quite satisfied’ or ‘very satisfied’ in ease of using a manual wheelchair compared with 68% of the respondents that were ‘quite satisfied’ or ‘very satisfied’ with the level of comfort. A greater satisfaction of ease in propulsion indoors compared with sitting comfort in various activities was found.

Conclusions.?A discrepancy was shown between users not being as satisfied with comfort in sitting in various activities as opposed to satisfaction with propulsion. This indicates the need for increased knowledge and developments concerning individual solutions, incorporating comfort as well as ease of use of a manual wheelchair.     

Preference Assessment in Toddlers with Mild Developmental and Physical Disabilities: A Comparative Study

In this study, a preference assessment involving presentation of pairs of toys was conducted with 10 toddlers with mild developmental and physical disabilities and a matched control group of 10 nondisabled toddlers. An exploration phase preceded the preference assessment. Our main findings were that (a) the pair-wise presentation method yielded a significant rank ordering of preferences in developmentally disabled toddlers, but not in the nondisabled toddlers; (b) dynamic toys were more preferred than nondynamic toys in disabled toddlers; but not in the nondisabled toddlers; and (c) for both nondisabled and disabled toddlers, the rank order of preferences established by the pair-wise presentation method did not significantly correlate with the rank order of preferences reported by the toddlers' parents and teachers.     

Wheelchair racing efficiency

PURPOSE: For individuals with disabilities exercise, such as wheelchair racing, can be an important modality for community reintegration, as well as health promotion. The purpose of this study was to examine selected parameters during racing wheelchair propulsion among a sample of elite wheelchair racers. It was hypothesized that blood lactate accumulation and wheeling economy (i.e. oxygen consumed per minute) would increase with speed and that gross mechanical efficiency would reach an optimum for each athlete. METHOD: Twelve elite wheelchair racers with paraplegia participated in this study. Nine of the subjects were males and three were females. Each subject used his or her personal wheelchair during the experiments. A computer monitored wheelchair dynamometer was used during all testing. The method used was essentially a discontinuous economy protocol. Mixed model analysis of variance (ANOVA) was used to compare blood lactate concentration, economy (minute oxygen consumption), and gross mechanical efficiency across the stages. RESULTS: The results of this study show that both economy and blood lactate concentration increase linearly with speed if resistance is held constant. The subjects in this study had gross mechanical efficiencies (gme) of about 18%, with the range going from 15.222.7%. The results indicate that at the higher speeds of propulsion, for example near race speeds, analysis of respiratory gases may not give a complete energy profile. CONCLUSION: While there is a good understanding of training methods to improve cardiovascular fitness for wheelchair racers, little is known about improving efficiency (e.g. technique, equipment), therefore methods need to be developed to determine efficiency while training or in race situations.     

The effect of visual biofeedback on the propulsion effectiveness of experienced wheelchair users

OBJECTIVE: To determine the effect of visual feedback on the propulsion effectiveness of experienced manual wheelchair users. DESIGN: Controlled trial. SETTING: A motion analysis laboratory. PARTICIPANTS: A convenience sample of 16 healthy men and 2 healthy women with T4-L2 traumatic paraplegia, a mean age of 38+/-9 years, and a mean duration of manual wheelchair-based mobility of 14+/-8 years. INTERVENTION: Propulsion was assessed as the subjects propelled an instrumented wheelchair (with and without visual biofeedback) on a custom-built dynamometer at propulsion intensities of .15 and .25W/kg for 10 minutes. MAIN OUTCOME MEASURES: The primary outcome variable was the fraction of effective force (FEF) (ie, the ratio of effective to total force) applied by the subject to the wheelchair's pushrim. Secondary variables included velocity, stroke frequency, and stroke angle. RESULTS: A 2-factor analysis of variance with repeated measurements was used to detect significant differences between the outcome variables. The FEF ratio was 73.9% without feedback and 72.5% with feedback at the lower-intensity level. Propulsion during the higher intensity condition both with and without feedback resulted in a statistically significant improvement in the FEF (73.9%-78.7% with no feedback, 72.5%-80.2% with feedback), compared with the lower-intensity level. Stroke angle increased from 84.3 degrees to 98.7 degrees and frequency decreased from 66 to 57.8 strokes/min with feedback. CONCLUSIONS: Visual biofeedback may have little utility in improving the force effectiveness of manual wheelchair propulsion in experienced wheelchair users. Experienced wheelchair users may have already optimized their stroke in a manner that balances energy expenditure with stroke efficiency. Other variables such as stroke length and frequency may be more amenable to visual biofeedback.     

Effects of synchronous versus asynchronous mode of propulsion on wheelchair basketball sprinting

Abstract

Purpose: This study aimed to first investigate synchronous (SYN) versus asynchronous (ASY) mode of propulsion and, second, investigate the wheel camber effects on sprinting performance as well as temporal parameters. Method: Seven wheelchair basketball players performed four maximal eight-second sprints on a wheelchair ergometer. They repeated the test according to two modes of propulsion (SYN and ASY) and two wheel cambers (9° and 15°).

Results: The mean maximal velocity and push power output was greater in the synchronous mode compared to the asynchronous mode for both camber angles. However, the fluctuation in the velocity profile is inferior for ASY versus SYN mode for both camber angles. Greater push time/cycle time (Pt/Ct) and arm frequency (AF) for synchronous mode versus asynchronous mode and inversely, lesser Ct and rest time (Rt) values for the synchronous mode, for which greater velocity were observed. Conclusions: SYN mode leads to better performance than ASY mode in terms of maximal propulsion velocity. However, ASY propulsion allows greater continuity of the hand-rim force application, reducing fluctuations in the velocity profile. The camber angle had no effect on ASY and SYN mean maximal velocity and push power output.

• Implications for Rehabilitation

• The study of wheelchair propulsion strategies is important for better understanding physiological and biomechanical impacts of wheelchair propulsion for individuals with disabilities.

• From a kinematical point of view, this study highlights synchronous mode of propulsion to be more efficient, with regards to mean maximal velocity reaching during maximal sprinting exercises.

• Even if this study focuses on well-trained wheelchair athletes, results from this study could complement the knowledge on the physiological and biomechanical adaptations to wheelchair propulsion and therefore, might be interesting for wheelchair modifications for purposes of rehabilitation.

     

Wheelchair racing efficiency

Purpose : For individuals with disabilities exercise, such as wheelchair racing, can be an important modality for community reintegration, as well as health promotion. The purpose of this study was to examine selected parameters during racing wheelchair propulsion among a sample of elite wheelchair racers. It was hypothesized that blood lactate accumulation and wheeling economy (i.e. oxygen consumed per minute) would increase with speed and that gross mechanical efficiency would reach an optimum for each athlete.

Method : Twelve elite wheelchair racers with paraplegia participated in this study. Nine of the subjects were males and three were females. Each subject used his or her personal wheelchair during the experiments. A computer monitored wheelchair dynamometer was used during all testing. The method used was essentially a discontinuous economy protocol. Mixed model analysis of variance (ANOVA) was used to compare blood lactate concentration, economy (minute oxygen consumption), and gross mechanical efficiency across the stages.

Results : The results of this study show that both economy and blood lactate concentration increase linearly with speed if resistance is held constant. The subjects in this study had gross mechanical efficiencies (gme) of about 18%, with the range going from 15.222.7%. The results indicate that at the higher speeds of propulsion, for example near race speeds, analysis of respiratory gases may not give a complete energy profile.

Conclusion : While there is a good understanding of training methods to improve cardiovascular fitness for wheelchair racers, little is known about improving efficiency (e.g. technique, equipment), therefore methods need to be developed to determine efficiency while training or in race situations.     

The effect of caster types on global rolling resistance in manual wheelchairs on indoor and outdoor surfaces

An important aspect of reducing the strain of wheeling is to decrease rolling resistance. Previous laboratory research, using a treadmill, determined that smaller casters significantly increased rolling resistance. The purpose of this study was to determine the effect of caster size on various indoor and outdoor surfaces on global wheelchair rolling resistance. Three caster types with sizes 4 in, 5 in, and 6 in, three indoor surfaces, and three outdoor surfaces were studied. A manual wheelchair was passively pulled along each surface at 1.11 m/s (3.64 ft/s) by a power wheelchair, and the global rolling resistance of the manual wheelchair was measured using a calibrated force transducer. A 3×3 repeated measures analysis of variance (ANOVA) was conducted for both indoor and outdoor environments. The 4-in casters resulted in the highest global rolling resistance on most surfaces. The 5-in casters had the least rolling resistance on most indoor surfaces, and the 6-in casters had the least rolling resistance on most outdoor surfaces. Although 4-in casters are more popular among active wheelchair users, larger casters were shown to have lower rolling resistance on most surfaces. This study may help users select the best caster size depending upon their daily activities and lifestyle.     

Muscle activity in the spinal cord-injured during wheelchair ambulation

Right shoulder complex muscles of nondisabled, paraplegic, and quadriplegic subjects were monitored with electromyography (EMG) during standardized wheelchair ambulation. It was shown that wheelchair ambulation required the recruitment of large amounts of available motor units in spinal cord-injured persons. Motor unit recruitments differed for the groups: recruitment was minimal for the nondisabled subjects, moderate for paraplegics, and often maximal for quadriplegics. In addition, large intra- and intergroup variabilities were found in the pattern of muscle recruitment during the standardized wheelchair ambulation movement. The high variability shown in the muscle recruitment patterns of the normal individuals was unexpected, because the ambulation movement had been standardized as much as possible. The technique used to monitor muscle activity in this study reflects an example of how EMG can be employed to analyze activity during a movement. Using this technique one can objectively determine if assumptions about what is occurring in a muscle group during activity are correct.